ResearchSpeak: low lymphocyte counts in MSers

Do you have a normal lymphocyte count? Do you know your lymphocyte counts? #ResearchSpeak #MSBlog #MSResearch

"The retrospective study below found that 1 in 10 DMT-naive MSers had low lymphocyte counts and in the majority of these no obvious cause could be found. The authors' suggest the lymphopaenia is due to autoimmunity, or is stress-induced through increased cortisol production or Epstein-Barr activation."

"I live and learn something new every day of the week about MS. I had no idea that ~10% of MSers had idiopathic (no apparent cause found) lymphopaenia. What is interesting that in this study low lymphocyte counts at baseline predicted low lymphocyte counts on treatment. Clearly these findings needs to be confirmed and explained. Who knows it may provide interesting insights into the pathogenesis of MS. I like the suggestion that it may be linked to stress and/or EBV reactivation."

"Lymphopaenia is one of the key battlegrounds in the marketing of DMTs. Low lymphocyte counts are an important risk factor for several serious adverse events on DMTs. Understanding MS-related lymphopaenia may help de-risk some of these DMTs. I am interested to know how many of you know what your latest lymphocyte counts are? If you don't you should find out and keep a record of it for yourself."

A lymphocyte: image source Wikipedia

Lim et al. Lymphopenia in treatment-naive relapsing multiple sclerosis. Neurol Neuroimmunol Neuroinflamm. 2016 Aug 12;3(5):e275. doi: 10.1212/NXI.0000000000000275. eCollection 2016.

Background: Lymphopenia accompanies some autoimmune diseases. Several studies, but not others, have suggested that lymphopenia occurs in treatment-naive multiple sclerosis (MS), so the issue remains unresolved.

Methods: Data were collected retrospectively during an institutionally approved service evaluation of blood test monitoring of patients with relapsing MS in a regional MS service in Southampton, UK, over a 2-year period (2012–2014). Control lymphocyte data were derived from preoperative blood counts of age- and sex-matched individuals undergoing septoplasty in the same hospital for structural reasons, excluding neoplastic and infective operative indications.

Results:  Seven hundred sixty-four patients were identified with blood test data (table). Baseline and post-treatment blood tests were available in 466 and 247 patients, respectively. Average blood test frequency was 4 per year. Lymphocyte counts were relatively stable with time, with a coefficient of variation of 7.5%. The mean lymphocyte count in treatment-naive patients with MS was 2.18 × 109/L with an SD of 0.66 × 109. Lymphopenia was present in 10% (48 patients; 46 grade I, one grade II, one grade III). In only 3 cases steroids were administered in the month before lymphopenia. There was no association between pretreatment lymphocyte count and any patient characteristic or month or season. 

Discussion: Since the lymphocyte reference range covers 95% of values in a healthy population, lymphopenia is expected in 2.5%. In our treatment-naive relapsing MS population, we found lymphopenia in 10%. Moreover, lymphopenia was not associated with relapsing activity. Hence, the lymphopenia in patients with MS is unlikely to be related to autoimmunity. A more likely explanation is stress-induced lymphopenia in both cohorts, through cortisol or Epstein-Barr activation.

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